First, I will give a brief background (it could be really long, but I am not up to writing so much)

My grandfather spent his life in the aviation industry, working for airlines, and eventually becoming a professor. Eventually, his influence hit me, and we found our bond, aviation. That bond lasted a very short time as he passed on less than two years after I discovered my love for aviation. When going through some of his "stuff," I found a few photos that he took of planes such as (I think) the DC-3 in the late-60's to early-70's.

Now my question:

Unfortunately, I have misplaced the pics as of now, but I intend on searching for them for a while this coming week. They are smaller than most common pictures today, but still of some quality, especially considering the time that they have been around. If I do find them, I would like to scan and upload them as a tribute to him, but, obviously, I don't have his permission. I would be relying on the written info on the back of each pic to tell me what is in the pic and where it was taken.

Am I allowed to do this, or would it still be considered a copyright violation?

Since your grandfather has passed on, these images AND their copyright are part of his estate which, presumably, your family has inherited. You, or your parents, now own the copyright to these pics unless your grandfather formally transferred the copyright elsewhere ... let's see 'em!